The electric mat switch of the present invention is concerned with treadles and floor mat devices responsive to persons walking, stepping or dropping articles on the mat for closing a switch in an electric circuit. Such devices are commonly used in conjunction with machines to shut down the same upon personnel movement toward the machine over the mat; in doorways and passages for signaling and actuating alarms, and other desired locations.
Heretofore, electric floor mat switches of this general type required very careful handling in storage, shipment and use to maintain the desired sensitivity of operation while preventing inadvertent damage resulting in switch closure or short circuiting. Toward this end, the prior art devices require shipment and storage in a flat condition, involving expensive crating and handling. Also, prior art electric mat switches required substantial hand work in manufacture to maintain the several layers properly positioned during assembly. The prior art presented further difficulties in that the separator layer was spaced inward from the sealed edge margin and therefore free to shift and dislocate or fold the foil sheets; or if the separator layer was secured to the margin then by its porous nature the moisture seal was often lost or reduced resulting in deterioration and shorting of the switch.
Representative of the prior art of which applicant is aware are the below listed patents:
______________________________________ U.S. Pat. No. PATENTEE ______________________________________ 3,243,540 Miller 3,754,176 Miller 4,137,116 Miller 4,200,777 Miller ______________________________________